X11 : Volountary locking up the keyboard ?
 

Hello, I would like that my childrens continue to do skype in fullscreen with their friends, but so that they do not remove the fullscreen: how to lock up the whole keyboard?
The mouse would allow to put back the keyboard? xscreensaver could have been envisaged but in that case the video of fullscreen skype remains static (They have openbox in their session) Any ideas are welcome. Thanks